JP2962418B2 - Microwave switch - Google Patents

Description

The present invention relates to a microwave switch in which a diode is connected in parallel or series / parallel to a microstrip line, and in particular, a non-reflection type microwave switch, Further, the present invention relates to a microstrip line suitable for forming a termination circuit of such a non-reflection type microwave switch.

[Prior Art] Conventionally, microwave switches can be roughly classified into eight types.
As shown in FIGS. 1A to 1C, a series type microwave switch in which a diode is connected in series to a microstrip line (FIG. 1A), and a type in which a diode is connected in parallel to a microstrip line. And a series-parallel type microwave switch in which a diode is connected in series / parallel to a microstrip line (FIG. (C)).

Although the above-mentioned series type microwave switch is easy to manufacture, it has a drawback that the insertion loss is large, the isolation is about 50 dB, and the characteristics as a switch are not preferable. On the other hand, the parallel-type microwave switch and the series-parallel type microwave switch have a small insertion loss, and in the case of the series-parallel type, the isolation can be made 60 dB or more.

By comparing these, as a microwave switch,
It can be seen that the latter and the microwave switches, especially the series-parallel type of microwave switch, have favorable characteristics.

[Problems to be Solved by the Invention] However, the parallel type microwave switch and the series parallel type microwave switch described above
There were the following problems.

That is, the performance of the microwave switch may need to be a non-reflection type. Conventionally, a non-reflection type switch is manufactured as the series-type microwave switch, which can satisfy this requirement. However, a non-reflection type microwave switch has not been manufactured for the parallel type microwave switch and the series / parallel type microwave switch.

Therefore, in order to make the microwave switch a non-reflection type, it must be a series type, and the insertion loss and isolation deteriorate. On the other hand, if the switch has excellent insertion loss and isolation, it cannot be made a non-reflection type. There was a problem.

Conventionally, the reason why parallel-type microwave switches and series-parallel-type microwave switches could not be made non-reflective was that the principle of the terminating resistor in the high-frequency range was not fully understood, and the desirable characteristics It is probable that the conditions required for maintenance were unclear.

That is, in the case of microwaves, the physical size and arrangement of the terminating resistors greatly affect the characteristics, so that it is not easy to set a preferable mode. In the case of a series-type microwave switch, the terminating resistor can be connected in a form branched from the microstrip line, so that this problem can be solved temporarily. However, in the case of the parallel-type microwave switch and the series-parallel-type microwave switch, it is not possible to connect the terminating resistor in the form of branching off the microstrip line. It is not easy to form.

As described above, in the conventional parallel-type microwave switch and series-parallel-type microwave switch, formation of an optimal termination circuit has been a problem to be solved.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object of the present invention is to maintain a preferable characteristic, configure an optimal termination circuit, and obtain a non-reflection type parallel type and a series parallel type. To provide a microwave switch.

Further, the present invention provides a microstrip line which can form an optimal termination circuit while maintaining the above preferable characteristics and is particularly suitable for realizing a non-reflection type parallel type or series parallel type microwave switch. It is in.

[Means for Solving the Problems] The present invention provides, as a means for solving the above problems, a microwave switch having a diode connected in parallel to a microstrip line; At a position, a terminating circuit configured by inserting and connecting a terminating resistor in series with the line and connecting a bypass diode to the terminating resistor in parallel is provided.

The present invention also provides a multi-pole microwave switch suitable as a changeover or selection switch.

That is, as a means for solving the above-mentioned problems, the present invention has one common port and a plurality of selection ports, and the common port and the selection port are connected by a switching element in which a series-parallel type diode is connected. And a microwave switch that selectively connects the switching ports, wherein a terminating resistor is inserted and connected in series with the microstrip line forming each of the selection ports at a position close to the parallel diode of the switching element, and It is characterized by including a termination circuit configured by connecting a bypass diode in parallel to a termination resistor.

In the circuit in which the terminating resistor and the bypass diode are connected in parallel, a discontinuous portion is provided in the strip conductor of the microstrip line, a concave portion is provided in a dielectric exposed at the discontinuous portion, and the discontinuous portion is provided. The main body of the bypass diode is connected so as to be bridged in the concave portion of the portion, and a chip resistor is stacked and connected as a terminating resistor thereon.

As a microstrip line constituting such a circuit, a discontinuous portion is provided in a strip conductor of the microstrip line, a concave portion is provided in a dielectric exposed at the discontinuous portion, and a concave portion of the discontinuous portion is provided. In the state where the main body of the bypass diode is positioned, it is connected so as to be bridged, and a chip resistor is laminated and connected as a terminating resistor thereon, and the resistor and the bypass diode are connected in parallel to form a microstrip. It is preferable to insert and connect in series in a line.

Further, the parallel connection of the resistor and the bypass diode is not limited to the diode and the chip resistor sequentially stacked and connected. May be inserted and connected.

The distance between the terminating resistor and the parallel diode is preferably reduced in order to minimize the connection distance required for their electrical connection. As this connection distance increases,
The inductance component increases and the characteristics deteriorate. That is, the reflection loss increases. Therefore, the connection distance between the terminating resistor and the parallel diode is preferably 0.
5 mm or less.

[Operation] The present invention has a configuration in which a terminating resistor is inserted and connected in series with the microstrip line at a position close to the parallel diode, so that an electrical connection between the terminating resistor and the parallel diode is provided. Is reduced, and the generation of an inductance component can be suppressed.

The relationship between the connection distance and the inductance tends to decrease as the distance decreases. FIG. 7 shows the relationship between the distance between the terminating resistor and the ground point and the reflection characteristics.

The graph of FIG. 7 shows the frequency (GHz) on the horizontal axis and the reflection loss (dB) on the vertical axis, and the length l (when a 50 Ω resistor is grounded by a 30 μφ lead (gold wire)). mm)
The relationship between the distance between the terminating resistor and the ground point and the reflection characteristics is shown using As shown in the figure, the reflection loss at each frequency increases as l increases from 0.2 mm to 0.9 mm. The inductance of the leads of each length is correspondingly between 0.15 nH and 0.7 nH.

From the figure, the return loss in the practical range is, for example, 18GH.
If Z does not exceed 11 dB, l ≦ 0.5 mm. Therefore, as described above, in the present invention, by setting the connection distance between the terminating resistor and the parallel diode as short as possible, preferably 0.5 mm or less, the reflection by mounting the terminating resistor to make it a non-reflective type. Losses are kept to a practically acceptable level.

Note that by using two lead wires in parallel, l
Even if ≦ 0.6 mm, the reflection loss can be prevented from exceeding 13 dB, and the reflection loss can be further reduced.

Further, in the present invention, a terminating resistor is arranged on the microstrip line, but a bypass diode is connected in parallel to the terminating resistor to prevent attenuation of a microwave to be transmitted.

Further, according to the present invention, by arranging a terminating resistor on the microstrip line, it is possible to reduce the occurrence of parasitic capacitance and inductance and to use it in a high frequency range. This effect is achieved by providing a discontinuous portion in the strip conductor of the microstrip line, providing a concave portion in the dielectric exposed at the discontinuous portion, and positioning the main body of the bypass diode in the concave portion of the discontinuous portion. It is connected so as to be bridged in a state where it is connected, and a chip resistor is stacked and connected as a terminating resistor thereon, and a resistor and a bypass diode connected in parallel are inserted and connected in series in a microstrip line. The configuration is more effective.

In addition, according to the present invention, since the terminating resistor and the parallel diode for shunt can be connected on the strip line, the manufacturing process is simplified. This function is not limited to the case where the resistor and the bypass diode are connected in parallel when forming the microwave switch and the microstrip line, not only when the diode and the chip resistor are sequentially stacked and connected, but they are integrally formed in advance. This is further effective by inserting and connecting the strip conductor to the discontinuous portion of the strip conductor.

Further, since the terminating resistor can be arranged on the microstrip line, the area required for arranging the terminating circuit can be reduced, and the size can be easily reduced. In particular, this effect is effective in a multi-pole microwave switch having a large number of selection ports, because the number of termination circuits to be provided increases.

Example An example of the present invention will be described with reference to the drawings.

<Configuration of First Embodiment> FIG. 1 shows a first embodiment of the microwave switch of the present invention.

This embodiment is an example that can be used as a non-reflective switch in the range of 1 to 18 GHz.

Microwave switch shown in the figure, a switch of a single throw type, and a coupling capacitor C ₁ and C ₃ provided on portions of the input and output terminals, a bias coil L ₁ and capacitor C ₂ , A reverse bias resistor R provided as a countermeasure when a large amplitude signal is input
₁ , a matching circuit 1, and a series-parallel connected series diode D _{1 serving} as a switching element,
A parallel diode D ₂ and D _3, configured to include a termination resistor circuit 2 consisting of the bypass diode D ₄ for bypassing the terminating resistor R ₂ and the termination resistor, and a bias coil L ₂ and capacitor C _4.

As the series diodes D _1, using the junction capacitance is small PIN diode. In this embodiment, a beam lead type diode is used and inserted and connected to a microstrip line.

The parallel diodes D ₂ and D ₃ are almost
It is desirable that they are arranged at a distance of 1/4 wavelength. In this embodiment, a PIN diode chip 12 is used as an element. This diode chip 12, as shown in FIG.
Inserted into a hole leading to the ground plane 8 provided in the dielectric of the strip conductor discontinuous portion of the microstrip line 3,
It is mounted by connecting to the ground plane 8 and connecting the upper electrode to the strip conductor 6 with the lead wire 13.

The terminating resistor R ₂ included in the terminating resistor circuit 2 has a resistance value of 50Ω, is connected in series to a line near the rear of the parallel diode D ₃ , and is grounded via the diode D _3. To form a termination circuit. Connection distance between the parallel diode D _3, as described above, and 0.5mm or less.

Further, this terminating resistor R _2, the bypass diode D ₄ is connected in parallel. The connection direction is set to the input signal so that it can be transmitted to the output side without a termination resistor R _2. It will be described later implementation of the terminating resistor R ₂ and the bypass diode D _4.

The above bias coil L ₂ and capacitor C _4, are connected in series, one end of the capacitor C ₄ is grounded. A connection point between the two is connected to a driver circuit (not shown) for supplying a bias current to the switching element of the switch, that is, the series diode D ₁ and the parallel diodes D ₂ and ₃ to turn on and off the switch. This driver circuit has a constant current supply circuit, and is configured to change the polarity of the output in accordance with the on / off state of the switch.

Termination resistor circuit 2 consisting of the terminating resistor R ₂ and the bypass diode D ₄ Prefecture, as shown in Figure 2, is placed on the microstrip line 3. This termination resistance circuit 2
As shown in FIGS. 3 and 4, the chip resistor 4 and the PIN
A diode 5; an electrode 4a of the chip resistor 4;
The PIN diode 5 is connected to 4b.

The chip resistor 4 forming the terminating resistor R ₂ is connected to the diode chip 12 forming the parallel diode D _3.
It is arranged close to. The terminating resistor R ₂ and the diode chip 12 is connected by a lead wire 13 made of gold.
In this embodiment, two lead wires 13 are used in parallel to reduce the inductance. The length of the lead wire 13, so that a 0.5mm or less, is set the arrangement interval between the termination resistor R ₂ and the diode chip 12.

The microstrip line 3 on which these are mounted is generally constructed by providing a layer of a dielectric 7 on a ground plane 8 and providing a strip conductor 6 made of metal on the dielectric 7 as shown in FIG. Is done. In the present embodiment, a discontinuous portion 6a is provided in a portion of the microstrip line 3 where the terminating resistor circuit 2 is mounted by removing the strip conductor 6 therefrom, and a dielectric material exposed at the discontinuous portion 6a is provided. 7 has a recess 7a. The concave portion 7a is formed in a size that can accommodate the PIN diode 5 so as not to contact the inner surface thereof when the terminal resistor circuit 2 is mounted.

As shown in FIG. 4, the termination resistor circuit 2 is mounted using a PIN
With the diode 5 facing down, the PIN diode 5 is inserted into the concave portion 7a so as not to contact the inner surface thereof, and the electrodes 4a and 4b of the chip resistor 4 are placed on the strip conductor 6 and a conductive material is provided between the two. This is done by electrically connecting and fixing with an adhesive 9 of the above.

The matching circuit 1 is a circuit for correcting the influence of the junction capacitance of the series diodes D ₁ is the switching element, constituting the inductance and capacitance connected in series. Specifically, on a stripline,
An inductance region and a capacitance region are formed.

<Operation of First Embodiment> Next, the operation of the present embodiment configured as described above will be described.

Microwave switch according to the present embodiment constructed as described above, when the not shown driver circuit functions to supply a constant current lower than the ground potential voltage, series diode D ₁ is forward biased, parallel diode D _{for 2} and D ₃ is a reverse bias state, the switch is turned on. As a result, the microwave current input, the capacitor C _1, the matching circuit 1, series diodes D _1, through the diode D ₄ and the capacitor C ₃ through the output side. In this case, the terminating resistor R ₂ is to be bypassed by the diode D _4, no loss due to this.

Then, when the polarity of the driver circuit described above is reversed, series diode D ₁ is reverse biased, the switch is turned off. As a result, the microwave current input is blocked in series diode D _1, and does not conduct. In this case, the output side is the termination resistor R ₂ and the parallel diode D ₂
And since the termination circuit is constituted by a D _3, a state in which the impedance of the output side is matched, the reflection of the microwave is prevented from entering from the output side.

<Configuration of Second Embodiment> FIG. 5 shows a second embodiment of the microwave switch of the present invention.

The present embodiment has one common port Pc and a plurality of selection ports Ps _{1 to} Ps _n, and the common port Pc and the selection port Ps
_{1 to} Ps _n are connected via a switching element whose on / off state changes by a bias, and the switching element is selectively turned on and off, and any _{one of} the selected ports Ps _{1 to} Ps _n is selectively connected to the common port Pc. This is an example in which the present invention is applied to a microwave switch that is connected to a microcomputer.

In the present embodiment, the common port Pc is opposite to a DC blocking capacitor C ₁ that is provided in a portion of the input terminal, a bias coil L ₁ and capacitor C _2, is provided as a countermeasure when a large amplitude signal inputted The circuit includes a bias resistor R ₁ and a matching circuit 1.

On the other hand, the selection ports Ps _{1 to} Ps _n have the same configuration, and include a series diode D ₁ , parallel diodes D ₂ and D ₃ functioning as switching elements, and a termination resistor.
Includes a termination resistor circuit 2 consisting of the bypass diode D ₄ to bypass the R ₂ and the termination resistor, the bias coil L ₂ and capacitor C _4, a DC blocking capacitor C ₃ which is provided in a portion of the output terminal It is composed.

These components are the same as those of the first embodiment described above, and thus the description will not be repeated.

<Operation of the Second Embodiment> In the present embodiment, each common port Pc and selected ports Ps _{1 to} Ps _{1 to} P
s _n and the switching elements of each selected port Ps _{1 to} Ps _n (series diode D ₁ , parallel diode D ₂ and D ₃ )
Connect by turning on and off. ON / OFF of the series diode D ₁ and the parallel diodes D ₂ and D ₃ is controlled by a driver circuit (not shown).

The termination circuit at the selected port connected to the common port operates in the same manner as in the case of switch-on in the first embodiment. On the other hand, the termination circuit at the selected port not connected to the common port operates in the same manner as in the case of the switch-off in the first embodiment.

<Other Embodiments> In each of the above embodiments, an example of a series / parallel type microwave switch has been described. However, the present invention can be applied to a parallel type microwave switch. In the case of a parallel type microwave switch, a terminating resistor may be provided on the input side.

Further, according to the present invention, as the terminating resistor circuit 2, one having a mounting structure different from that of the above embodiment can be used.
FIG. 6 shows an example.

Termination resistor circuit 2 shown in the figure, the microstrip line 3, provided discontinuity 3a, this discontinuity 3a, and the terminating resistor R ₂ and the bypass diode D ₄ which constitute the the termination resistor circuit 2 It is configured by inserting.

As shown in FIG. 6, the terminating resistor circuit 2 includes a chip resistor 4 and a PIN diode 5, and the PIN diode 5 is connected to the electrodes 4a and 4b of the chip resistor 4.

The microstrip line 3 on which these are mounted is formed by laminating a dielectric 7 and a strip conductor 6 on a ground plane 8, and the discontinuous portion 3 a is composed of the dielectric 7 and the strip conductor 6.
And is removed. The discontinuous portion 3a is formed to have a size into which the chip resistor 4 can be inserted when the termination resistor circuit 2 is mounted.

As shown in FIG. 6, the termination resistor circuit 2 is mounted using a PIN
The chip resistor 4 is connected to the discontinuous portion 3a with the diode 5 facing upward.
And the electrodes 4a and 4b of the chip resistor 4 are connected to the strip conductor 6 and the lead wire 11.

FIG. 6 shows a mode in which the terminating resistor circuit 2 is inserted and connected to a normal microstrip line. However, in order to form a terminating circuit, as shown in FIG. Place and adjust the length of the lead wire 11,
For example, it is set to 0.5 mm or less.

The microstrip line constituting the terminating resistance circuit 2 used in each of the above embodiments is not limited to the switch in each of the above embodiments, but can be applied to other types of microwave switches. The present invention is not limited to this, and can be applied to other microwave circuits.

[Effects of the Invention] As described above, the present invention provides a parallel type and a series / parallel type microwave switch which can form an optimal termination circuit while maintaining preferable characteristics and can be of a non-reflection type. Can be realized.

Further, the present invention provides a microstrip line which can form an optimal termination circuit while maintaining the above preferable characteristics and is particularly suitable for realizing a non-reflection type parallel type or series parallel type microwave switch. be able to.

Further, according to the present invention, the occurrence of parasitic capacitance and inductance is reduced, enabling use in a high frequency range.
Also, there is an effect that a microwave switch which is simple in manufacturing process, requires a small area for disposing a termination circuit, and can be easily miniaturized.

Further, according to the present invention, a microstrip line suitable for a configuration of a microwave switch having such a termination circuit can be obtained.

[Brief description of the drawings]

FIG. 1 is an equivalent circuit diagram showing a first embodiment of the microwave switch of the present invention, FIG. 2 is a plan view of a main part showing a microstrip line in which a termination resistor circuit is inserted and connected, and FIG. 3 is an example of a termination resistor circuit. FIG. 4 is a sectional view of a main part showing a mounting structure of a termination resistor circuit on a microstrip line, FIG. 5 is a circuit diagram showing a second embodiment of the microwave switch of the present invention, and FIG. FIG. 7 shows another example of a termination resistor circuit that can be used in the present invention, and is a cross-sectional view of a main part showing a mounting structure of the termination resistor circuit on a microstrip line. FIG. FIGS. 8A to 8C are graphs showing the relationship between the connection distance and the reflection characteristics, and FIGS. 8A to 8C are equivalent circuit diagrams showing the basic configuration of various microwave switches. C ₁ -C ₃ ...... capacitor L _1, L ₂ ...... coils D ₁ to D ₄ ...... diodes R _1, R ₂ ...... resistor 1 ...... matching circuit 2 ...... terminating resistor circuit 3 ...... microstrip line 3a … Discontinuous part 4… chip resistance 4a, 4b… electrode 5… PIN diode 6… strip conductor 7… dielectric 7a… recess 8… ground plane 9… adhesive 11, 13… Lead wire 12 …… Diode chip

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-112401 (JP, A) JP-A-60-206202 (JP, A) Fully open Showa 62-64001 (JP, U) Really open Showa 58- 85375 (JP, U) Real opening 60-114402 (JP, U)

Claims (4)

(57) [Claims] 1. A microwave switch having a diode connected in parallel to a microstrip line, wherein a terminating resistor is inserted and connected in series with the microstrip line at a position close to the parallel diode on the microstrip line. A terminating circuit configured by connecting a bypass diode to the terminating resistor in parallel; and a bias coil and a capacitor connected in series and connected to an output terminal of the bypass diode and configured to flow a bias current through the terminating circuit. A microwave switch, wherein switching is performed by changing the polarity of a bias current flowing from the connection point of the series-connected bias coil and capacitor to the termination circuit. 2. A micro-switch having one common port and a plurality of selection ports, and selectively connecting the common port and the selection port by a stable switching element having a series-parallel type diode connected thereto. In the wave switch, a terminating resistor is inserted and connected in series with the microstrip line constituting each of the selection ports at a position close to the parallel diode of the switching element, and a bypass diode is connected in parallel with the terminating resistor. And a series-connected bias coil and a capacitor connected to the output terminal side of the bypass diode and supplying a bias current to the terminal circuit. Changing the polarity of the bias current flowing from the connection point of the coil and capacitor to the above termination circuit Ri microwave switch and performs switching. 3. A discontinuous portion is provided in a strip conductor of the microstrip line, a concave portion is provided in a dielectric exposed at the discontinuous portion, and a main body of a bypass diode is provided in the concave portion of the discontinuous portion. Are connected so as to be bridged in a state where they are positioned, and a chip resistor is laminated and connected as a terminating resistor thereon, and this resistor and a bypass diode are connected in parallel and inserted in series into a microstrip line. The microwave switch according to claim 1 or 2, wherein the microwave switch is connected. 4. The microwave switch according to claim 3, wherein a diode and a chip resistor which are stacked in advance and connected in parallel are connected so as to be bridged in a state where the body of the diode is located at the discontinuous portion.